Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
354 AM EDT Mon Oct 22 2018

Valid 12Z Mon Oct 22 2018 - 12Z Thu Oct 25 2018


Days 1 through 3...

***Central Rockies***

The broad upper level trough currently over central California is
forecast to slowly move east with some positive vorticity
advection within the base of the trough.  As the upper level
trough approaches the Four Corners region by Tuesday, moisture
advection and mid level dynamics are maximized over western
Colorado and will result in the greatest opportunity for
accumulating snow for elevations above 10000 feet.  The San Juan
Mountains will likely have the greatest amounts, with patchy areas
of greater than 4 inches possible above treeline by Wednesday
morning for southwest facing slopes.  Light snow amounts are also
expected for the Uinta Mountains in northeast Utah.


***Northern New England***

A strong shortwave impulse tracking southeastward across Ontario
Monday is forecast to amplify further upon reaching New England by
Tuesday night.  The accompanying surface low is expected to
re-form near Nova Scotia by early Wednesday morning and intensify
as it lifts towards the north.  A band of moderate snow is likely
to the north and west of the surface low across northern Maine and
extending westward to the White Mountains of northern New
Hampshire, with the greatest snowfall associated with where the
low-mid level frontogenesis sets up.  There is a moderate
probability of 4+ inches across northern Maine Tuesday night and
into Wednesday morning. 

The probability of significant icing (0.25 inches or more) is less
than 10 percent all three days.

Hamrick